There's no denying that the Internet contains a lot of material that most parents wouldn't want their children to see. Whether it's pornography, hate speech, chat rooms or gambling sites, many parents worry that their children will be exposed to negative or even dangerous content. While some opponents of censorship may feel that parental supervision is the best way to keep kids safe online, many parents point out that it's difficult -- if not impossible -- to oversee a child's access to the Internet all the time.

Many parents turn to software and hardware solutions to this problem. They can purchase Web filtering programs like Net Nanny or CYBERsitter to block access to undesirable Web sites. These programs usually have a series of options parents can select to limit the sites their children can access. These options tell the program which filters to enable. For example, CYBERsitter has 35 filter categories, including pornography and social networking sites [source: CYBERsitter].

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Most Web filters use two main techniques to block content: Blacklists and keyword blocking. A blacklist is a list of Web sites that the Web filter's creators have designated as undesirable. Blacklists change over time, and most companies offer updated lists for free. Any attempt to visit a site on a blacklist fails. With keyword blocking, the software scans a Web page as the user tries to visit it. The program analyzes the page to see if it contains certain keywords. If the program determines the Web page isn't appropriate, it blocks access to the page.

Another option for parents is to install a firewall. A computer firewall provides protection from dangerous or undesirable content. Firewalls can be software or hardware. They act as a barrier between the Internet and your computer network. They only let safe content through and keep everything else out. Firewalls require a little more involvement from the network administrator (in this case, a parent) than Web filtering software. Tech-savvy parents might not have a problem installing and maintaining a firewall. Others prefer to use Web filters, which do most of the work for them.

Have you ever tried to access a Web site at your workplace only to receive an intimidating message? Some companies limit the kinds of sites employees can visit. Learn about Internet censorship from the corporate standpoint on the next page.

Web Filter Controversy

Censorship opponents have some big problems with Web filtering software. Many Web filtering programs encrypt their blacklists, claiming that it helps minimize abuse. Opponents point out that the encrypted blacklist could also include Web pages that aren't inappropriate at all, including pages that criticize the creators of the Web filter. Even if the programs' creators aren't blocking these sites on purpose, it's easy for a Web filter to restrict access to the wrong sites. That's because programs that search for keywords can't detect context. For example, early Web filters would often block access to chicken breast recipes. The programs couldn't tell the difference between an innocent site about cooking and a pornographic site, so they blocked all of them indiscriminately.